Hydraulic ball race grinder



Feb. 4, 1936. A. P, STEINER Er Alu.. 2,029,511

HYDRAULIC BALL RACE GRINDER Filed oct. 22. 1929 15 sheets-Sheet 1 innunnni (and: IE

abtomq A. P. sTElNER ErvAL 2,029,511

HYDRAULIC BALL RACE GRINDER Feb. 4, 1936.

Filed oct. 22, 1929 15 sheets-sheet 2 Amod P Stel/'2er E' ar? Wine (1151501 wat,

Feb. 4, 1936.

A. P. STEINER T AL HYDRAULIC BALL RACE GRINDER Filed oct. 2.2, 1929 l5 Sheets-Sheet 3 gwnow r 1 Amm TSeiner Edgar? W im? Haro/:IE Ba ldiger Feb. 4, 1936. A. P. STEINER ET AL HYDRAULIC BALL RACE GRINDER Filed 0G13. 22, 1929 15 Sheets-Sheet 4 \\\\\|lllllll Feb.' 4, 1936.

A. P, STEINER ET AL HYDRAULIC BALL RACE GRINDER Filed ont. 22, 1929 15 Sheets-Sheet 5 Feb. 4, 1936. A. P. STEINER ET AL HYDRAULIC BALL RACE GRINDER 15 sheets-sheet e Filed Oct. 22, 1929 gmmko'c Steiner rP Wme cubane IFeb. 4, 1936.

A. P. s'rElNER ET AL HYDRAULIC BALL RACE GRINDER 15 sheets-sheet 7 Filed Oct. 22, 1929 gmemtou mod PSzeinel' Edgar? Wine` Ham/4 ff. B [Alger Feb. 4, 1936. A. P. STI-:INER E1' AL 2,029,511

HYDRAULIC BALL RACE `GRNDER y Filed Oct. 22, 1929 15 Sheets-Sheet 8 g'fwwtozd Amad PStez'ner EdgarFWz'ne- 15 Sheets-Sheet 9 Feb. 4, 1936. A. P. STEINER Er Al.`

HYDRAULIC BALL RACE GRINDER Filed Oct. 22.l 1929 15 -Sheets-Sheet l0 A. P. ST1-UNER 1-:1 AL

vHYDRAULIC BALL RACE GRNDER Filed het. 22, 1929 Feb. 4, 1936.

Feb. 4, 1936. A, pf STEINER Er A1. 2,029,511

HYDRAULIC BALL RACE GRINDER Filed Oct. 22, 1929 vl5 Sheets-3h66?I ll iinganm saw Feb. 4, 1936. A. P. sTElNER ET AL HYDRAULIC BALL ACE GRINDER Filed Oct. 22, 1929 15 Sheets-Sheet l 2 w u .w r W W awww 1% M WM @MMC H Feb. 4, 1936. A. P. STEINER ET AL HYDRAULIC BALL RAGE GRINDER 15 Sheets-Sheekl 13 Filed Oct. 22. 1929 MS s@ 1.11. hnnumhubf Feb- 4, 1936- I A. P. STEINER Er AL 2,029,511

HYDRAULIC BALL RACE GRINDER Filed oct. 22, 1929 15 sneetssheet 14 il? al", dfaldiger A Feb. 4, 1936.

Aj P. STEINER Er AL Y HYDRAULIC BALL RACE GRINDER l5 Sheets-Shea?l 15 Filed Oct. 22, 1929 mm E INVENTORS Hmoa R'el'ner. Edgar hline.

Patented Feb. 4, 1.936

Pit'r-lz'rrry oFFlcE HYDRAULIC BALL RACE GRINDEB Amos P. Steiner, Edgar P. wine, ma imola E. Balsiger, Waynesboro, Pa., assignors to Landis Tool Company, Waynesboro, Pa., a corporation of Pennsylvania Application October 22,

This invention `relates to grinding machines and more particularly to a grinding machine which is utilized for grinding internal surfaces i'n which the diameter of the surface to be ground is greater than the diameter of the opening through which the tool must be passed to reach the surface.

An object of the invention is to provide an eficient means for oscillating the head stock wherein the operating parts are few in number iand free from any lost motion in their operaion.

A furtherobject of the invention is to provide 'a machine of the above type wherein the head stock is osciilated by a means whereby'the rate of oscillation and the extent of oscillation may be adjusted independently one of the other.

A still further object of the invention is to provide 'a machine of the above type wherein the means which positions the grinding wheel for its grinding operation may be independently controlled for positioning the same for dressing.l

Further objects and advantages will become apparent as the description proceeds. l

Referring to the accompanying drawings, which are made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is a front elevation of the machine, Figure 2 is an end elevation of the machine, Figure 3 is a'plan view of the machine,

Figure 4 is a front elevation ot the wheel base showing operating cylinders and fluid conduits thereto in outline, Y

A Figure 5 is an end elevation of the wheel base,

Figure 6 is a front elevation of the wheel carriage driving cylinder,

Figure 7 is an end elevation showing the wheel base driving cylinder,

Figure 8 is a front elevation of head stock assembly,

Figure 9 is alight-hand end elevation of the head stock with the chuck removed, being sub- :tantially a view of Figure 8 as viewed from the right, 1

Figure 10 is a sectional end elevation of the oscillating mechanism, taken substantially on line lul-m if-Figure 1,

Figure l1 is an end elevation of the control valve assembly,

Figure 12 is al front elevation partly in section of the control valve assembly andthe oscillatory rev rsing mechanism,

, igure 13 is a section on line |3-I3, of Fig. 15,

Figure 14 is a front section of the auxiliary .control valve taken on line iii-I4 Of Figure 16,

1929, Sel'lalNo. 401,500 (Cl. 51-97) Figure 15 is an end section of the auxiliary control valve taken on line I5I5 of Figure 16,

Figure 16 is a plan view of the auxiliary control valve,

Figure 17 is a section on line- II-Ii of Figure 16 showing the arrangement of the needle valves andthe check valves, Q

. Figure 18 is a view showing the position of the head stock for grinding races for end thrust bearings,

Figure 19 shows the position of the head stock for grinding inside races for ball bearings,

Figure 20 shows the position of the head stock for grinding outside races for ball bearings and also the path followed by the grinding wheel in moving from inoperative position to dlamonding position or to working position, i

Figures 18a, 19a and 20a are perspective views of the work on an enlarged scale corresponding to that shown in Figures 18, 19 and 20, respectively, l

Figure 21 is a front elevation of the wheel truingdevice,

Figure 22 is an end elevation of the wheel truing device,

Figure 23 is a longitudinal sectional view of the wheel carriage cylinder,

Figure 24`is a longitudinal section of the wheel base operating cylinder, and

Figure 25 is a diagrammatic view showing the hydraulic system.

In a co-pending application Serial No. 389,492, filed August 30, 1929, there is shown, described and claimed a grinding machine for grinding the internal surface of a work piece wherein the grinding wheel is moved by hydraulic means axially into the work piece at a rapid-rate and then transversely into grinding position.- In this type of "machine, thve work piece must be rotated and oscillated during grinding. The present invention has particularly to do with. the means which rotates and osciliates the work piece. This y is accomplished by mounting the work holder on the head stock so that it may be rotated and the In the drawings reference character 30 indilcates the bed of a. grinding machine having a longitudinally movable wheel carriage 3| mounted in guideways thereon. A wheel base 32 is mounted to slide on a wheel base slide 33 which in turn is mounted on a sub-slide 34 on the wheel carriage 3|. The wheel base and the wheel base slide are mounted to slide transversely of the wheel carriage. A grinding-wheel 35 is mounted on a shaft rotatably mounted in the wheel base 32 and is driven by means of a belt 36 from a pulley 31, the pulley 31 being in turn driven by means of a belt 38 on a pulley 39 on the end of the shaft of a motor 40 (see Figures 1 to 3).

As shown in Figure 1.a head stock 4| is mounted to move transversely of a support 42 in guideways 43. The support 42 may be moved longitudinally of a table by means of an adjusting screw 44. A head stock spindle mounted in the head stock carries a work chuck 45 in its forward end in which chuck is mounted the work 41. The work is covered by a guard 46. The work is rotated by means of a fluid motor 48 driven by pressure fluid delivered thereto through a pipe 49, the details of all of which will be more fully presented as the description proceeds.

The means for moving the wheel carriage longitudinally of the bed of the machine and for moving the wheel base transversely of the bed of the machine will now be described (Fig. 5). The wheel base 32 is slidably mounted on the subslide 33 and is actuated by means of a hand wheel 58 mounted in a bracket on the said slide. 'I'he hand Wheel is secured on the front end of a shaft 5| which is threaded at its other end for engagement with a nut 52 secured to the under side of the Wheel base 32. Means associated with the wheel base operating mechanism provides for taking up back-lash between the shaft 5| and the wheel base 32. `This consists of a pin 53 slidably mounted in a bracket 54 and fixed in a bracket 55 attached to the rear end of slide 33. A spring 56 on the said pin between the bracket 54 and a head 51 on the said pin exerts a force tending to slide wheel base 32 toward rear of slide 33 thus taking up back-lash between the threaded shaftand the nut 52.

The wheel carriage 3| is chambered to provide a cylinder 58 having a piston 59 movable therein (Figs. 3, 4, 6 and 23) A piston rod 60 is secured to the piston 59 at `one end and at the other end to a bracket 6| on the bed of the machine so that when pressure fluid enters the cylinder 58 the cylinder moves and the piston remains stationary. It should be noted that the piston rod 60 is relatively large so that the surface area on the piston 59 at the right of the piston is relatively small so that the pressure fluid acting on this side will be considerably-less than that on the left or front side o1' the piston 59. Pressure fluid is delivered to the cylinder 58 through fluid lines 62 and 63 (Figures 1 to 1, 23 and 24). Admission of fluid to and from lines 62 and 63 is controlled by a valve 8| (Fig. 1), the details of which will be described later. The wheel carriage 3| is also chambered to provide a cylinder 65 in which a piston 66 is mounted having a piston rod 61 which is attached at its outer end to a lug 68 on the wheel base (Figures 4, '1, 23 and 24).

A baille plate 69 in the line 62 directs fluid 'first into the cylinder 58 through passage 1|).

Fluid from line 62 also goes to the cylinder 65l through passage. The purpose of the baille plate is to'cause pressure fluid' to act more quickly in the cylinder 58 than in the cylinder 65. When the grinding wheel is to be withdrawn pressure fluid is directed through the line 63 directly into cylinder 65 and into cylinder 58 through the passage 80. Since the pressure fluid acts first on the larger area on the front side of the piston 59 in the cylinder 58 the grinding wheel carriage is flrst moved to position the grinding wheel Within the work and then the wheel base is moved to place the grinding wheel in contact with the Work, since the area at the right of the piston 66 in Y cylinder 65 is much less than the area on the face of the piston A59 in cylinder 58. An arm 12 is pivoted on a bracket A55 on the wheel base and one end of the arm engages the sub-slide 34 and the other end engages the end of a piston rod of the hydraulic feed regulator 14 (Figures 4 and 5) From the construction of the pivoted arm 12 it will be seen that the feed regulator moves a greater distance thanthe wheel support. This construction increases the accuracy of the feed in proportion to the relative lengths of the distance from the pivot point of the lever to each end. The feed regulator is of 'che well known dash pot type. A pipe 16 is connected to the front end of' the cylinder and connects through needle valve 11 with the reservoir 15. A pipe 18 also connects reservoir 15 with pipe 16. Pressure fluid is forced from the cylinder on the inward movement of the slide and passes through the pipe 16 and needle valve 11 to reservoir 15. Check valves 19 prevent said fluid from going any way except through the needle valve. On the return movement of the slide pressure fluid is drawn from the reservoir through the pipe 18, check valves 19 into the line 16 and thence into the cylinder 14. The rate with which the Wheel base may be moved toward the work is controlled by adjustment of the needle valve 11 which restricts the flow of fluid from the cylinder 14 into the reservoir 15. -To withdraw the grinding wheel base and the grinding wheel carriage, fluid is delivered through line 63 to the left of piston 66, a part of the fluid passing through line 8U to the right of piston 59. The fluid acting on a greater surface area on piston 66 than on piston 59 first moves the wheel base back and then moves the wheel carriage 3| to the right. Admission of fluid to the cylinders 58 and 65 is controlled by a valve assembly 8| shown at the right of Figure 12 and in Figures 14 and 15, details of which valve will be more fully described as the descriptionproceeds. From the preceding description it can be seen that such a structure is of great value in grinding ball races or other 4 internal work having a plurality of inside diameters in which the tool must first pass through a portion of' minimum diameter before it may reach a position from which it may be advanced to grindl a portion of greater diameter. The sequence of movements described is necessary to grind this type of Work and the structure disclosed above provides this sequence automatically by fluid under pressures.

Head stock assembly :top in the table and extends down vertically through the bed of the machine, being rotatably supported in bearings 85 on the bed of the, ma-

chine. 'I'he lower end of the spindle extends intoA the casing of a motor 86 and has the motor .propeller 88 secured thereon. The motor casing has suitable packing 89 to prevent leakage of fluid past the spindle 84 which spindle is a shaft on the motor propeller 88. 'I'he motor 86 is any suitable oscillating motor preferably of the type which has blades which have fluid-tight t withinl the casing. The spindle 84 is hollow to provide a iiuid conduit 80 to which a pipe 9| is connected at the lower end and which has a radial port 92 at its upper end to which the fluid conduit 49 is connected. At its upper end the spindle also has an axial bore 93 which has a radial bore 94 at its upper end. This radial bore is connected with a flexible conduit 95 connected to the exhaust passage of the motor 48. A radial bore l 96 at the lower end of the bore 93 permits exhaust from the motor to drop into the base of the machine (Figs. 9 and 10).

The means for oscillating the head stock assembly just described will now be described. This consists of a valve assembly 91 vwhich will be hereinafter referred to as the control valve assembly and consists of a start and stop valve 88 and a reversing valve 99. The details of these valves are best givenin Figures 12 and 25.

The reversing valve 98 is used to control the operation of the oscillating motor 86. The motor 06 may be of any well known type of oscillating motor having blades which have a fluid tight fit within a casing. Pressure fluid is delivered fromA a pump to-the valve assembly. A pair of spaced disks |0| and |02 operating on a valve stem |03 control passage o'f uid from inlet port |04 to line |05 to the reversing valve 99 and to A. port |06 to exhaust line |01, respectively. A neele valve |08 contrnls passage of fluid through line to the valve chamber 99. Valve disks |09 and H0 control passage of fluid from the line |05 to ports and ||2 which connect with -fiuid lines ||3 and ||4 respectively to the oscilv lating motor 86. The exhaust from the motor 8S passes through the passage ||6 or ||1 to passage H3 which passes through the motor casing and has an exhaust line 9 connected thereto. The valve disks |09 and I|0 which control admission of iiuid to the oscillating mot-or are shifted in the following manner. A valve stem to which the disks |09 and ||0 are connected is'connected by an arm |2| to a bar- |22 slidable in a bracket |23. A lever |24 is pivoted upon the valve casing at |25 and has its lower end in 'engagement with the bar |22 so that movement of the lever will slide the bar in the brackets |23 in which it is mounted. The reversing lever4 |24 is actuated by dogs |26 adjustably mounted cn sliding dog rack |21. The dog rack |21 is slidablyA mounted in the base of the machine and is operated by a segmental gear |28 which is secured to the oscillating spindle 84. It will readily be seen from the description so fargiven that as the shaft 84 nears one extreme of its oscillationv one of the dogs |26 will strike the lever |24 to shift the valve disks |09 and ||0 to cha-nge the direction of fluid into the motor 86 to reverse the motor. A compression spring |29 is positioned beneath the lower valve disk |02 to hold the Valve normally in the elevated position in which it is shown in Figure 12. in this position fluid may pass from the inlet |04 through the valve chamber to the fluid passage |05. The valve stem |03 is operated by means of a cam |30 onfthe lower end of a lever i3 l. This cam is pivoted in a part of the bracket |23 which is broken away to better reveal'its parts. When the lever |3| is in its extreme left position the valve disk |02 is depressed to its lowermost position so that pressure fluid may enter the said valve through |04, pass through port |06 and return through line |01 to a reservoir in the base of the machine, not shown. When in this position pressure fluid is by-passed from the pump and none of the elements of the head stock are operating.' When the lever |3| is in the vertical position the port |06 is closed and port |05 is cut -ofl from the port |04 so that pressure fluid can neither be by-passed nor pass to the oscillating motor 86. f Pressure fluid, however, may continue to pass to pipe 9| and to the Work drive j.

motor 48 as will later appear.

disk engages one end of a lever |33. The lever |33 is pivoted at |34 to the valve casing and has its free end in engagement with-a spool |35 on the lower end of a rod |36.

As bestl shown in Figures 14, 15 and 25 a valve |31 comprising a pair of spaced disks |38v and |39 is mounted in the valve chamber |40 and slidably mounted on the uppei end of the rod |36. The valve disks |38 and |38 control passage of fluid from pressure fluid line |4| to line 62 and The lower end of the stem |03 has a disk |32 secured thereon which 63, passage of iluid to the lines 62 and 63 being controlled by needle valves |42 and |43 respectively. An exhaust line |44 conducts fluid back to a reservoir in the base of the machine. 'I'he valve |31 is held in balanced position between springs |45 and |46. The spring |46 is positioned between the disk |38 and the upper end of the chamber |40 and the spring |45 is positioned between the disk |39 and a collar on the rod |36. Operation of the lever |3| will therefore control admission of iluid to the wheel base and Wheel carriage motors to operate them. The valve 0| which will hereafter be referred to. as the auxil-A lary valve is mounted on the bed of the machine adjacent the main control valve 91, and controls only movements of the Wheel base and the wheel carriage. When the work is being ground on the machine this valve is operated inconjunction asv with the main control valve through the lever mechanism |33 just described. When the grinding wheel, however, needs dressing it is not necessary to oscillate the head stock or to drive the work drive motor. Mechanism is therefore provided for controlling the valve 8| independently of the main control valve i. e. independently of the lever I3 Mounted on the auxiliary valve 8| is a lser |41. This lever is secured on a shaft which has a gear segment |48 which engages teeth |49 on a rack |50. The rack |50 is integral with or has on its lower end a pair of operating ngers |5| which move freely in a guide |52 cn the rod |35.

The lingers |5| are free to move on the guide is operated by the main control valve through the. Y

Y lever |33 and is held in position between springs |45 and |46. Pressure fluid enters the valve chamber through the line |4| and port |53 from which it is directed through ports |54 or |55 to lines 63 or 62 depending on the position of the valve |31 and is delivered to the wheel base and wheel carriage cylinders. The needle valves |4' and |42 control passage of fluid to lines 63 and 62 respectively. Aspring pressed check valve |53 is positioned in a bore connecting port |55 and line 62 to permit 'fluid to flow freely from line 62 to port |55, and a similar check valve |51 is positioned between port |54 and line 63 (Fig. 251

In the position shown, pressure fluid enters the valve and is directed through port |00, needle valve |42 to the pipe 62 through which it is conducted to the cylinders 06 and 00 to move them into operative position to bring the grinding wheel within the work and in grinding contact with the work. When the operating lever |3| is in the extreme left of the position, the disks and |02 of the start and stop valve are in position to bypass pressure iiuid from port |04 to |06 which would otherwise pass to the reversing valve 00 and the work drive motor. With the main control valve in this position, the auxiliary valve |01 is in the top position and the wheel carriage and the wheel base will be withdrawn to inoperative position. In order to bring the grinding wheel to dressing position the lever |41 must be moved to the dot and dash line position |08 shown in Figure 14, in which position the valve |01 is moved down to operative position sliding on the rod I 06 against the action of spring |45.

As shown in Figures 1, 25 and 12 a single fluid conduit |00 supplies pressure fluid to the main control valve 01 and a branch |60 of this line leads to the work drive motor. Pressure fluid entering through control valve assembly through passage |04 may be directed either to the oscillating motor 00 through the reversing valve 06 or it may be by-passed through port |00 and passage |01 depending on the position of the valve disks |0| and |02. If the by-pass is open all the uid coming through the pipe |00 is returned to the reservoir. If the fluid is directed to the reversing valve it is placed under pressure and-a part of it passes vthrough passage |60 and 00 to the work drive mo'-` tor 40. With this arrangement the work head cannot oscillate without the work drive motor operating. The work drive motor, however, may

rotate without the oscillating motor by shifting the lever |0| to vertical position so that the valve disks |0| and |02 close of! ports |04 and |00, but do not open by-pass port |00, allowing the iiuid to pass out of the valve assembly through the work drive motor in order to operate this motor. Adjustable pressure relief valves |6| and |02 may be positioned in the pressure lines |00 and |4| from the pump 00.

Wheel dressing mechanism The wheel dressing mechanism is shown best in Figures 21 and 22 and consists of a bracket |00 secured to a bracket |04 which latter bracket is secured to the bed of the machine. An arm |00 is pivotally mounted on the bracket |60 so as to be permitted to swing forward to place a dressing tool |00 in position to dress the grinding wheel 00. 'I'he bracket |00 has a positive stop |01 which is engaged by an adjustable stop |60 on the arm |00. This enables the operator to position the dressing tool in exact operative position. A clamp |00 holds the tool in any position in which it may be set. The dressing tool |00 is held in an arm |10 which is pivotally mounted on the end of the arm |00 and may be rotated by an arm |1| so as to give a curved face to the grinding wheel 00 which is being dressed. A connecting rod |12 is attached to the arm |00 by a stud |10. The other end of the connectingV rod is connected to an arm |14 which is pivoted at |10 and carries a resilient stop |10. This stop has a reduced portion |11 and is slidably mounted in a hollow drilled in the larm |14 to provide a running nt for' both diameters of the said stop. A spring |10 is mounted on vthe reduced portion of the stop. A pin |10 limits the action of the spring |10. An adjustable stop |00 serves to limit the movement of the wheel carriage whether it is moving to working position or dressing position. When the diamond is dropped into position for dressing the stop |16 is raised by means of the connecting rod |12 and the arm |14 so that it rests directly in the path of the wheel carriage 3|. A hardened block 0| is inserted in said carriage to engage the stop. As the carriage engages the stop the stop is moved against the action of the spring |10 until it engages adjustable stop |00. The carriage is thus stopped so that the grinding wheel is in correct position for dressing. 'I'he length of the stop |16 is the same as the distance from the center of the groove in the work piece to the center about which the dressing tool rotates. A pin |02 extends down through arm |60 on the same axis about which the diamond rotates. This pin has a plurality of diameters |00 adjacent the diamond |66 The diamond may therefore be set for a given radius by adjusting it to engage any one of the desired shoulders |60 which represent different diameters of the pin |62.

A coolant pump |04 driven by a belt |05 from the motor 40 delivers cooling uid through aexible conduit |06 and through the head-stock spindle 20 to the interior oi the work 41. A reversing valve 00 (Fig. 25) is positioned in the fluid line 40 and enables the operator to rotate the work 41 in either direction. 'Ihe speed of the iiuid motor 40 is controlled by means of a needle valve |01.

As will be seen from the structure described the single lever |0| controls the oscillating motor 06 for the head-stock support and the work rotating motor 40. It likewise controls movement of the work carriage and the wheel base into and out of operative position. It will therefore be seen that the single lever provides a convenient control for all of the mechanism necessary during a grinding operation. When it is desired to dress the grinding wheel, this may be done by operating another lever which controls the movement of the wheel base and the wheel carriage into wheel dressing position without affecting the operative mechanism for the head-stock assembly. It will therefore be seen that by providing mechanism for controlling the machine by means of a. single lever operation of the machine is greatly simplified thus requiring less attention on the part of the operator and allowing him to give more of his thought to other things and even to operate more than a single machine at a time. The wheel dressing mechanism moreover insures positioning the grinding wheel in exact position to be dressed with the least possible loss of time.

It will be obvious to those skilled in the art that various changes may be made in our device without departing from the spirit of the invention and therefore we do not limit ourselves to what is shown in the drawings and described in the specification but only as indicated in the appended claims.

Having thus fully described our said invention, what we claim as new and desire to secure by Letters Patent, is:

1. A grinding machine. having a head-stock support, a head-stock mounted'on the support. means for oscillating the head-stock support, and means for rotating the head-stock, a grinding wheel, means for moving the grinding wheel axially and transversely of the head-stock, all o! saidmeans being fluid operated and a single con? trol lever for controlling operation of all of the Said means, and independent control means for work to position the grinding wheel in wheel dressing position, substantially as set forth.

2. A grinding machine having a head-stock' support, a head-stock mounted on the support, means for oscillating the head-stock support, and

means for rotating the head-stock, a grinding wheel, means for moving the grinding wheel axially and transversely of the head-stock, fluid pressure means for operating all of said means, a single control lever for controlling operation of all of the said means, independent control means for causing the grinding wheel to move axially of the work to position the grinding wheel in wheel dressing position, and resilient means for stopping movement of the work carriage in wheel dressing position, substantially as set forth.

3. In a grinding machine for ball races, -a headstock, means for rotating the head-stock, means for oscillating the head-stock, a single valve for controlling the head-stock rotating and the'headstock oscillating means, a lever for controlling said valve, the said lever operating in one position to permit rotation of the head-stock without oscillating it, substantially as set forth.

4. In a machine for grinding ball races, a base, a Wheel support mounted thereon, a headstock support, a head-stock mounted thereon, means for moving the wheel support in two directions at right angles to each other on the support, means for rotating the head-stock, means for oscillating the head-stock, a valve for controlling the operation of the rotating and oscillating means, another valve positioned adjacent' said valve, operative connection between the two valves whereby operation of one valve operates the other to control movement of the wheel support into grinding position, substantially as set forth.

5. In a grinding machine, a head-stock, a

r Wheel carriage, a wheel base movable transversely of the wheel carriage, pressure fluid means for rotating the head-stock, separate pressure fluid means for oscillating the head-stock, pressure fluid means for moving the Wheel carriage axially of the head-stock, separate pressure iuid means for moving the wheel base transversely of the Wheel carriage, 4a valve for controlling rotation and oscillation of the head-stock, a second valve for controlling movement of the wheel carriage and the wheel base, operative connection ,between the rst and the last-named valve whereby operation of one will operate the other, substantially as set forth.

6. In a grinding machine, a head-stock, a wheel carriage and a wheel base, pressure fluid means for rotating the head-stock and for oscillating it, pressure fluid means for moving the wheelcarriage axially of the head-stock, additional pressure iiuid means for moving the wheel base transversely of the wheel carriage, a valve for controlling rotation and oscillation of the head-stock, a valve for controlling movement of the wheel carriage and the wheel base, the said last-named valve being operated by the firstnamed valve, and independent means for operating the last-named valve whereby the wheel carriage and the wheel base may be operated when the head-stock oscillating and rotating means are inoperative, substantially as set forth.

7. A grinding machine comprising a base, a

mounted in the wheel base, a head-stock having means for oscillating and rotating the same, and a. Wheel dressing mechanism movable into position to dress the grinding wheel, means for controlling oscillation and rotation of the headstock, means for controlling movement of the wheel carriage and the wheel base, s aid lastnamed means being controlled by the first-named means, and independent means for causing movement of the wheel carriage and the wheel base to position the grinding vwheel adjacent the wheel dressing means, substantially as set forth. 8. In a machine for grinding ball races, a bed, a wheel carriage and wheel base mounted thereon and movablelongitudinally and transversely of said bed, a head-stock, means for rotating the head-stock, means foroscillating the head-stock, the last-named means comprising a spindle vertically mountedin the said bed and attached to the said head-stock. a fluid motor for driving said spindle, a valve for directing pressure fluid to oscillate said fluid motor to oscillate the headstock, a uid conduit through said spindle for supplying pressure fluid to the head-stock rotating motor, the said valve operating in one position to cut olf fluid from the said oscillating motor and the said work rotating motor and in another position to cut oi motive fluid only from the oscillating motor but to permit the work rotating motor to continue to operate, substantially as set forth.

9. In a grinding machine, a base, a headstoel-r,` a wheel carriage movable longitudinally of said base and axially of said head-stock, a

wheel base movable transversely of the wheel carriage, a wheel dresing mechanism mounted on said base and movable into the path of the said wheel, an arm on said Wheel dressing mechanism having a stop secured thereon ,said stop being positioned in the path of the Wheel carriage when the dressing tool is moved to position to dress the grinding wheel, and means for moving the wheel carriage and the wheel base into position for placing the grinding wheel in the wheel dressing position, substantially as set forth.

10. In a machine for grinding ball races, a bed, a Wheel carriage and wheel base mounted thereon and movable longitudinally and transversely of said bed, a head stock, means for rotating the headstock, means for oscillating the headstock, the last-named means comprising a spindle vertically mountel in the said bed and attached to the said headstock, a fluid motor for driving said' spindle, a valve for directing pressure fluid to oscillate said fluid motor to oscillate the headstock, a fluid conduit through said spindle for supplying pressure uid to the headstock rotating motor, substantially as set forth.

11. A grinding machine comprising a head' stock, a grinding wheel, a grinding Wheel carria'ge movable toward and from said head stock, means for moving said wheel carriage, a hydraulic feed regulator having a movable element thereon for limiting said movement, and

means mounted on said carriage and operably engaging said movable element for causing said wheel carriage to move toward the work at a slower rate than the movement of said regulator whereby any errors in the regulator will be 'decreased in the movement of the wheel carriage, substantially as set forth.

12. A grinding wheel comprising a work support, a wheel support, a wheel slide, a uid motor for moving one of said supports toward the other, a hydraulic feed regulator having a mov- 

